Understandable then that Mercer's chief comeback wish is to "work my way back in the lineup and help this team win. That's all you can ask for."
That did not happen immediately -- not the day after incumbent shortstop Jung Ho Kang's first career two-homer game fueled Saturday's 3-2 win over the Giants. Kang remained at short for Sunday night's game with San Francisco.
"We'll get him into game action sooner rather than later," manager Clint Hurdle said of Mercer. "There's no hiding when you get out there at shortstop; we'll find out rather quickly [where he is physically]. But I heard he is in a very good place."
Hurdle heard that from Indianapolis manager Dean Treanor in a conversation four hours prior to the club announcement of Mercer's reinstatement. To create roster room for him, the Bucs placed Travis Ishikawa on the disabled list with lower back strain.
The manager also heard it from Mercer himself.
"He says he made all the plays [in Indianapolis] and felt confident of being in a good place," Hurdle relayed.
Mercer had gone on the DL on July 20, the day after suffering a sprained left knee and bruised lower left leg when upended on a play at second base in Milwaukee.
Mercer had gone on rehab assignment on Aug. 11 to Indianapolis, where he played seven games. He went 6-for-25 with a homer and three RBIs, and underwent a thorough test of his mobility in the field.
"I'm doing well. Had to make some plays in the hole, and it all went well," said Mercer, confirming lateral mobility as the biggest hurdle. "I'm ready to go. There's nothing holding me back. I'm still wearing a little brace [on the knee], to help with support. I hope to get out of it eventually.
"Now I just have to go out and perform. It's awesome to be back. I missed these guys; this is a very tight-knit group. It's good to be back with my second family."
Ishikawa has hit .222, with a homer and eight RBIs, in 33 games since the Bucs picked him up on waivers from the Giants on July 5. He has an on-base percentage of .409 in 22 pinch-hitting plate appearances. He had not started a game since last Sunday, in New York.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer and on his podcast. This story was not subject to the approval of Major League Baseball or its clubs.